Field of the Invention
The present invention relates to a multiple material golf club head with an improved attachment region between parts of the head. More specifically, the present invention relates to a golf club head with a composite crown having a scarf joint attachment configuration with a face component of the head.
Description of the Related Art
Golf club manufacturers often combine metallic golf club head bodies with composite crowns to reduce the overall head mass and lower the clubs' center of gravity, thus improving the mass properties of such multiple material heads. The region where the crown is affixed to the body with an adhesive material is typically known as the bond joint. In prior art multiple material golf club heads, manufacturers often employ a lap joint, or “step” structure, examples of which are shown in FIGS. 1 (disclosed in U.S. Pat. No. 6,623,378) and 2 (disclosed in U.S. Pat. No. 6,969,326), at the intersection between the crown and the body. This “step”-type prior art structure, though relatively straightforward to manufacture, is problematic because it creates a high-stress area at the front of the bond joint, which means that a great deal of stress is placed on the adhesive when the golf club head impacts a golf ball. This causes the crown to separate from the body at the bond region, which becomes visible to a golfer after repeated use and often leads to permanent damage to the club. The prior art discloses other types of bond region structures, including a basic scarf joint shown in FIG. 3 (disclosed in U.S. Patent Application Publication Number 2015/0045134), but this structure is not optimized to address the significant stresses placed on the bond region and other parts of the golf club head when the head repeatedly impacts golf balls.
Therefore, there is a need for an improved bond region structure that can be manufactured efficiently and that minimizes the significant stresses of impact that cause separation of the crown from the body.